i would say to your mum that she needs to do something about it otherwise you cant stay there esepcially after the baby has arrived as it wont be a safe stable home to bring the child up in.
if she doesnt do anything then all ican say is either call the police on him or the only thing you can do is leave otherwise you will end up having social services involved as the baby will be the subject of racism and emotional abuse being brought up in an enviroment like that and it will probably end up with your baby being taken away from you as they will look at it as you allowed it to happen by staying there or not instigating something to be done about the situation.
i know its unfair but this is how social services are working now a days, and also if you baby is taken away then at such a young age 9 times out of 10 the baby tends to get put straight into the adoption service so something does need to be done now.
you and your mum need to do something, stand up to him and dont back down. xx